The Wireless Personal Area Network (WPAN) not only supports wireless connection of an audio/video device, a computer, a peripheral device, and the like, which are located within a short distance of 10 m, but also supports communication between small, low-power multimedia devices which are easy to carry, thereby supporting a variety of services.
In accordance with a distributed Medium Access Control (MAC) method for the WPAN suggested by the WiMedia-Alliance, basically, MAC not only makes each of the variety of devices transmit its own beacon frame and analyzes beacon frame information of neighboring devices thereby adjusting basic timing with neighbors, but also individually controls Quality of Service (QoS), hibernation mode, security, and the like in a distributed fashion.
The distributed MAC method for the WPAN has an advantage in that it is easy to establish a network in a wireless environment where devices are frequently connected and disconnected since each device individually manages the network, unlike a method in which a specific device manages the network in a centralized fashion. However, the distributed MAC method for the WPAN has a problem in that there is a lot of information for analysis of neighboring devices and it may take a rather long time and may waste resources to find a compromise between neighboring devices. Particularly, the wireless resources of the WPAN may be significantly wasted if not all devices have a mechanism for optimally allocating wireless resources such that indispensable wireless resources alone are allocated.
FIG. 1 illustrates a structure of a distributed MAC superframe of a general WPAN.
As shown in FIG. 1, a superframe 100 includes a Beacon Period (BP) 102 and a Data Period (DP) 104. The BP 102 includes Beacon Time Slots (BTSs), each 85□us long, and the DP 104 includes Medium Access Slots (MASs), each 256□us long.
FIG. 2 illustrates relations of communication of beacon frames, command frames, and data frames between neighboring devices in a general WPAN.
As shown in FIG. 2, in a network established by devices 200, 202, and 204, each device selects an unused BTS among a number of BTSs illustrated in FIG. 1 and transmits its beacon frame in the selected BTS. A device identifier (ID), its own BTS information, medium usage information, and the like of each device are transmitted by incorporating them into a beacon frame of the device. As shown in FIG. 2, each device negotiates with each other using a specific Information Element (IE) field of a beacon frame in the BP 102 shown in FIG. 1 or using a command frame in the DP 104, and thereby reserves MASs in the DP 104 to prevent competition and collision of data transmitted in the DP 104.
Despite the advantage in that it is easy to establish a network in a wireless environment where devices are frequently connected and disconnected since each device individually manages the network, the conventional distributed MAC method for the WPAN described above has a problem in that there is a lot of information to be analyzed for establishing a network with neighboring devices and it may take a rather long time and may waste wireless resources to find a compromise between neighboring devices.